3-Dimensional Conformal Radiation Therapy in Treating Patients With Bladder Cancer Who Have Undergone Transurethral Resection of the Bladder

RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Specialized radiation therapy that delivers a high dose of radiation directly to the tumor may kill more tumor cells and cause less damage to normal tissue. PURPOSE: This phase I trial is studying the side effects and best dose of 3-dimensional conformal radiation therapy in treating patients with bladder cancer who have undergone transurethral resection of the bladder.